Pbesstjre-gage for steaffi-boilers



E. H. ASHCROFT.-

Pressure Gage.

Patented March 6, 1860.

No; 27,341. v

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EDYVARD H. ASHCROFT, OF BOSTON, MASSACHUSETTS.

PRESSURE-GAGE FOR STEAM-BOILERS.

Specification of Letters Patent No. 27,341, dated March 6, 1860.

To all whom it may concern:

Be it known that I, EDWARD H. ASH- oaor'r, of Boston, in the county ofSuffolk and State of Massachusetts, have invented an ImprovedPressure-Gage for Steam- Boilers; and I do hereby declare the same to befully described and represented in the following specification and theaccompanying drawings, of which Figure 1, denotes a front view: Fig. 2,a longitudinal section, and Fig. 3, a transverse section of a pressuregage provided with my invention.

For moving the indicator or index pointer of a steam pressure gage ithas been customary to apply to its arbor, a small gear or pinion toengage with a rack extended upward from the diaphragm (or the springthereof,) of the gage. Besides this, a retractive spiral spring has alsobeen applied to the arbor of the indicator for the purpose of bringingback the indicator as the pressure of the steam may slacken. It willreadily be seen that when the pressure of the steam is great, or fiftyor one hundred pounds to the square inch, the spi *al spring will bevery much contracted, and as a matter of course will cause the bearingteeth of the pinion and rack to bear quite hard against one another. Nowunder these circumstances, when a steam pressure gage is in use on alocomotive steam engine in movement 011 a railway, the undulations ofthe track will produce such a jolting or jarring of the engine, as tokeep the tooth surfaces in contact in continual movement on one another,more or less. This movement, under the great pressure of the springexerted to force one tooth against the other, soon materially wears theteeth, and seriously affects the efficiency and accuracy of the gage.

The object of my invention has been to overcome the above mentioneddifliculty. In doing so, I discard the rack and pinion entirely, and inthe place of the pinion, I affix on the arbor, a, of the index pointer,b, of the gage (see Figs. 1, 2-, 3,) a wheel or barrel, 0. To this wheelI affix one end of a chain (Z, and wind such chain around the peripheryof the wheel and fasten the outer extremity of the chain to the upperend of the superior arm of a bent lever, 6, arranged within the gagecase A, and so as to turn on a fulcrum f, as shown in Fig. 2. Theinferior arm of the said lever is jointed to a rod or bar, g, soconnected with the elastic diaphragm, h, as to be moved thereby andtherewith. As the pressure of the steam increases, the superior arm ofthe bent lever will be moved out-ward, and so as not only to draw on thechain and rotate the wheel or barrel, 0, and the arbor of the indicator,but to wind up the spiral retractive spring, 2', of the indicator arbor.In this way, the index hand will be moved over its divided plate orlimb, k, and owing to the application and arrangement of the workingparts, the jar and movements of the 10- comotive engine, when thepressure gage is used thereon, and such engine is in use, will createnone of the rubbing and wear of the surfaces and perturbations of theindicator, such take place when the rack and pinion are employed asdescribed. My improvement though simple is one of great value in thepressure gage.

I do not claim the usual arrangement and application of a rack andpinion to the index pointer, and the diaphragm of a steam pressure gage,nor do I claim any application of gearing to the index pointer in orderto operate it, for it has been an object with me to avoid the use of anygears or racks of any kind, or any devices, which by the constantjarring of the locomotive engine while it may be in movement on arailway, could wear or become injured.

I am aware, that in a pressure gage, a shaft connected with an indexpointer shaft by two gears, has not only been operated or turned in onedirection by a flexible strip or belt coiled around it and attached to alever resting on the diaphragm spindle, but has also been moved orturned in the opposite direction by a heavy pendulum or weight appliedto an arm projecting from the shaft. Such devices or mechanism foroperating the index pointer shaft, would be subject to such movements,if employed on a locomotive engine boiler, as to destroy or materiallyinjure their efiiciency. The constant vibrations which would beproduced, in the weight would generate in it such momentum andpercussive force as not only to very soon destroy the teeth of thegearing, but subject the index pointer to such continual and extensivevibrations on its are as to render it difficult to ascertain by it theproper pressure of the steam. In my improved gage, I apply a coiledspring directly to and so as to coil around the indicator shaft, and tocooperate with a chain cl, and lever, 6, arranged and applied to it andthe diaphragm rod d, as hereinbefore described and as shown in thedrawings. Now, although the spring serves to rotate the index pointershaft in one direction, its rotation in the opposite direction beingproduced by the lever and chain the coils of the spring are so arrangedthat the action of the locomotive engine or the jars and shocks of itWhile running on a railway can produce no improper swayings ordeflections of the index pointer, such as Would take place Were aWeighted arm or pendulum applied to the indicator shaft. Thus, it Willbe seen that in my invention of my improved gage, the spring and thechain and lever do something more than merely effecting the rotations ofthe indicator shaft, for the arrangement of the lever is such that theportion of the chain extending from it to the index pointer shaft ishorizontal or about so, and consequently thus prevents the verticalshocks of the engine from affecting the index pointer.

My improved gage is perfect in its operation, the index pointermaintaining great steadiness under equality of pressure Whatever may bethe speed of the engine or the amount of shocks or jarring of itproduced by inequalities or irregularities of the rail- Way track.

lVllat therefore I claim is My improved locomotive engine boiler steamgage as made With the coiled spring the chain and lever arranged andapplied directly to the diaphragm rod and the index pointer shaft inmanner and so as to operate substantially as described.

E. H. ASHCROFT. Witnesses R. H. EDDY,

F. P. HALE, Jr.

